If we do not get anything to drink for about three weeks, we will die. When we feel thirsty, our body tells us to replenish its liquid supply. Thirst occurs by a change in the salt content of our blood.
There is a certain normal amount of salt and water present in our blood. When the balance changes by having more salt in blood, we feel thirsty.
In our brain, there is a part called ‘Thirst Centre’ which responds to the amount of salt in our blood. Whenever, there is a change in the balance, it sends messages to the back of the throat, which then travel to the brain, making us feel thirsty.
Below Thirsty info from Wikipedia (Read More):-
Thirst is the craving for fluids, resulting in the basic instinct of animals to drink. It is an essential mechanism involved in fluid balance. It arises from a lack of fluids and/or an increase in the concentration of certain osmolites such as salt. If the water volume of the body falls below a certain threshold, or the osmolite concentration becomes too high, the brain signals thirst.
Continuous dehydration can cause myriad problems, but is most often associated with neurological problems such as seizures, and renal problems.
Excessive thirst, known as polydipsia, along with excessive urination, known as polyuria, may be an indication of diabetes.
http://en.wikipedia.org/wiki/Thirsty
